用linq查询得到的Var 变量查找指定索引的元素报错 求指点问题在哪里？

                        var q = from c in db.out_call where c.result != 1 && c.isAuto == 0 && c.outcallCount < c.outCallMaxCount select c;

                        if (q != null && q.Count() > 0)

                        {



                            for (int a = 1; a < q.Count(); a++)

                            {

                                anologCh = 1;

                                for (int i = 0; i < nMaxCH; i++)

                                {

                                    if (ShDll.SsmGetChType(i) == 0 && ShDll.SsmGetChState(i) == 0 && SsmGetLineVoltage(i) > 10)

                                    {

                                        anologCh = i;

                                        break;

                                    }



                                }

                                if (anologCh == -1)

                                    continue;

                                phone=q.ElementAt(a).phoneNum .ToString().Trim();

phone=q.ElementAt(a).phoneNum .ToString().Trim();
这一行会出错错误是
LINQ to Entities 不识别方法“SoundStudyTest0010.out_call ElementAt[out_call](System.Linq.IQueryable`1[SoundStudyTest0010.out_call], Int32)”，因此该方法无法转换为存储表达式。
 求教怎么解决？ 
------解决方案--------------------
var q=....
q=q.ToList(); 
。。。。。